Artifacts on burned roms

[SlawDog]

Not sure if this is the correct section as I'm not really dealing with homebrew here.   I made an eprom cart so I could play some of the rare games I'll never pay for.  I have tried a few different setups and all have this issue.   There are what look like blocks in the background of every game I try to burn.  Store bought games don't have this problem.   I have tried it with the eprom straight on the cartridge PCB and shielded to ground.  I currently have the setup pictured with a ribbon cable coming out of the cart I have also wrapped this in masking tape and then covered in aluminum foil and tied the foil to ground.   No change.   I have tried different rom images of the same games and tried different 2732's all the same.  Any ideas? 

 

 

Edited March 5 by SlawDog

[smarty]

Could it be the speed of the Eprom's you have not being fast enough? I assume your programmed Roms are verifying correctly once programmed, have you tried with a shorter ribbon cable on your adapter.

[Thomas Jentzsch]

These are RF artifacts. You need better shielding. This has already been discussed on AtariAge, so you will find details and solutions when you search for them.

[Keatah]

Yes better shielding.

 

Just having that ribbon cable with its many wires close together is enough to cause issues. Conductor separation isn't even being considered here. And EEPROMS can and do have different electrical characteristics to begin with.